Semiconductor device including recessed interconnect structure

ABSTRACT

A semiconductor device includes a first gate structure extending along a first lateral direction. The semiconductor device includes a first interconnect structure, disposed above the first gate structure, that extends along a second lateral direction perpendicular to the first lateral direction. The first interconnect structure includes a first portion and a second portion electrically isolated from each other by a first dielectric structure. The semiconductor device includes a second interconnect structure, disposed between the first gate structure and the first interconnect structure, that electrically couples the first gate structure to the first portion of the first interconnect structure. The second interconnect structure includes a recessed portion that is substantially aligned with the first gate structure and the dielectric structure along a vertical direction.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experiencedexponential growth. In semiconductor IC design, standard cellsmethodologies are commonly used for the design of semiconductor deviceson a chip. Standard cell methodologies use standard cells as abstractrepresentations of certain functions to integrate millions, or billions,devices on a single chip. As ICs continue to scale down, more and moredevices are integrated into the single chip. This scaling down processgenerally provides benefits by increasing production efficiency andlowering associated costs.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a cross-sectional view of an example semiconductordevice including a recessed interconnect structure, in accordance withsome embodiments.

FIG. 2 illustrates a cross-sectional view of another examplesemiconductor device including a recessed interconnect structure, inaccordance with some embodiments.

FIG. 3 illustrates a circuit diagram of an example circuit, inaccordance with some embodiments.

FIG. 4 illustrates an example layout design of a standard cellrepresenting the circuit of FIG. 3, in accordance with some embodiments.

FIG. 5 illustrates a cross-sectional view of a semiconductor device,formed by at least a portion of the layout design of FIG. 4, thatincludes a recessed interconnect structure, in accordance with someembodiments.

FIGS. 6A and 6B illustrate example layout designs of a standard cellrepresenting the circuit of FIG. 3, in accordance with some embodiments.

FIG. 7 illustrates a perspective view of a semiconductor device, formedby at least a portion of the layout designs of FIGS. 6A-B, that includesa recessed interconnect structure, in accordance with some embodiments.

FIG. 8 illustrates a flowchart of a method of manufacturing asemiconductor device, in accordance with some embodiments.

FIG. 9 illustrates a block diagram of a system of generating an IClayout design, in accordance with some embodiments.

FIG. 10 illustrates a block diagram of an IC manufacturing system, andan IC manufacturing flow associated therewith, in accordance with someembodiments.

FIG. 11 illustrates a flow chart of an example method for forming asemiconductor device including a recessed interconnect structure, inaccordance with some embodiments.

FIGS. 12A, 12B, 12C, 12D, 12E, 12F, 12G, 12H, 12I, 12J, 12K, 12L, and12M illustrate cross-sectional views of an example semiconductor deviceduring various fabrication stages, made by the method of FIG. 11, inaccordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

With the trend of scaling down the ICs, in general, the area of astandard cell shall be scaled down accordingly. The area of the standardcell can be scaled down by reducing a cell width of the cell and/or acell height of the cell. The cell width is typically proportional to anumber of gate structures or features (e.g., typically known as “POLY”),extending along a vertical direction, that the cell can contain; and thecell height is typically proportional to a number of signal tracks,extending along a horizontal direction, that the cell can contain. Whilereducing the cell height (e.g., by decreasing the number of signaltracks), the cell width (the number of gate structures) may be subjectedto being increased, which may not efficiently reduce the total area.Although the number of gate structures can be forced to be unchanged(e.g., only reducing the number of signal tracks), fabricating asemiconductor device based on such a cell design can encounter variousrouting issues. For example, one or more interconnect structures may beformed (e.g., cut) to have relatively shorter width, partially due tothe shortened cell width. It can become significantly difficult whenlanding an interconnect structure (e.g., a via structure) on such ashortened interconnect structure, which can likely cause a functionalfailure (e.g., a short circuit) of the cell.

The present disclosure provides various embodiments of a semiconductordevice that can be represented by (or formed based on) a standard cell.An area of the standard cell can be reduced by concurrently reducing acell height and a cell width of the standard cell, while being immunefrom the issues that existing technology encounters. For example, thesemiconductor device includes a number of transistors, each of whichincludes respective gate structure and source/drain structures. The gatestructures can be respectively defined by a plurality of gate featuresof the cell, which are associated with the cell width of the cell. Thegate structures and the source/drain structures can be connected by aplurality of interconnect structures, which are respectively defined bya number of signal tracks of the cell. The semiconductor device, asdisclosed herein, includes one or more recessed interconnect structureseach disposed between at least one corresponding gate structure and atleast one corresponding interconnect structure. In some embodiments, therecessed interconnect structure can include a partially or fullyrecessed portion that is filled with a dielectric material. For example,a recessed interconnect structure, including a partially recessedportion, can laterally extend or shift the connection point of acorresponding gate structure, which causes a corresponding interconnectstructure to be shifted accordingly. Thus, other interconnect structures(e.g., the interconnect structures adjacent to the interconnectstructure connected to the gate structure) shall not be cut to have ashortened lateral width. As such, despite of reducing a number of thegate features and a number of the signal tracks of the cell (therebyreducing a total area of the cell), the above-identified issues that theexisting technology is facing can be resolved. In some otherembodiments, the recessed interconnect structure, including a fullyrecessed portion, can vertically shift the connection point of acorresponding conductive structure (e.g., one or more interconnectstructures connected to the dummy gate structures and/or dummysource/drain structures), which allows an interconnect structure in aninterconnect layer to be formed over the recessed interconnectstructure. As such, routing resource of that interconnect layer can beadvantageously reserved.

Referring to FIG. 1, a cross-sectional view of a portion of asemiconductor device 100, including a recessed interconnect structure,is depicted, in accordance with some embodiments. It is understood thatthe semiconductor device 100, as shown in FIG. 1, is simplified forpurposes of illustration, and thus, the semiconductor device 100 caninclude any of various suitable features while remaining within thescope of the present disclosure. For example, the semiconductor device100 may include a plurality of transistors (e.g., planar complementarymetal-oxide-semiconductor field-effect transistors (NMOSFETs), fin-basedfield-effect transistors (FinFETs), nanosheet field-effect transistors,nanowire field-effect transistors), each of which is formed byrespective gate structure and source/drain structures (or source/drainregions), while the illustrated embodiment of FIG. 1 may include some ofthe structures.

As shown, the semiconductor device 100 includes a first gate structure102, a second gate structure 104, and a third gate structure 106 formedover a substrate (not shown). In some embodiments, the gate structures102-106 may include a conductive material such as, for example, one ormore metal materials, a polysilicon material, etc. Although not shown inFIG. 1, it is understood that each of the gate structures 102-106 isformed over one or more active regions (e.g., one or more conductionchannels) with corresponding source/drain structures/regions disposed onthe sides of the gate structure to function as a respective transistor.The source/drain structures can source/drain conduction current throughthe active region, which is gated (e.g., modulated) by the gatestructure. For example, each of the gate structures 102-106 may beformed over (e.g., to straddle) the active region of a FinFET tomodulate current conducting through the FinFET. Such functionalstructures of a transistor (and other active devices, for example,resistors, capacitors, etc.) are collectively referred to asfront-end-of-line (FEOL) structures. The gate structures 102-106 areembedded in a dielectric layer 108. The dielectric layer 108 may includea dielectric material such as, for example, a low-k dielectric material,a ultra-low-k dielectric material. Such a dielectric layer 108 istypically referred to as an inter-layer dielectric (ILD) layer.

The semiconductor device 100 further includes an interconnect structure116 formed over the dielectric layer 108. In some embodiments, theinterconnect structure 116 may include a conductive material such as,for example, one or more metal materials. The layer containing such aninterconnect structure 116, that is formed immediately above the gatestructures, is sometimes referred to an “M0” layer. Typically, thestructures formed in and above the M0 layer (e.g., M1 layer, M2 layer,etc.) are collectively referred to as back-end-of-line (BEOL)structures. To enable the intended functionality of the semiconductordevice 100, each of the gate structures 102-106 may be electricallycoupled to one or more BEOL structures. For example, the gate structure102 is electrically coupled to an interconnect structure 116-1 of theinterconnect structure 116; and the gate structure 104 is electricallycoupled to an interconnect structure 116-2 of the interconnect structure116. The interconnect structures 116-1 and 116-2 may be formed along thesame signal track and separated (e.g., isolated) from each other by adielectric structure 118.

The gate structure 102 can be electrically coupled to the interconnectstructure 116-1 through an interconnect structure 110 extending throughthe dielectric layer 108; and the gate structure 104 can be electricallycoupled to the interconnect structure 116-2 through an interconnectstructure 112 extending through the dielectric layer 108. In someembodiments, the interconnect structure 110 may be formed as a viainterconnect structure. Such a via interconnect structure 110, whichconnects a gate structure to an interconnect structure in the M0 layerthat is vertically aligned with the gate structure, is sometimesreferred to as a “VG.”

According to various embodiments of the present disclosure, theinterconnect structure 112, which connects a gate structure to aninterconnect structure in the M0 layer that is not vertically alignedwith (e.g., laterally displaced from) the gate structure, may be formedto include a recessed portion 112-1 and a non-recessed portion 112-2. Assuch, the interconnect structure 112 may be referred to as a partiallyrecessed interconnect structure. The recessed portion 112-1 andnon-recessed portion 112-2 may be formed as respective via structuresthat are abutted (or otherwise adjacent) to each other. The location ofthe recessed portion 112-1 might have been used to form a via structure(typically referred to as “VG”) to connect the gate structure 104 to aninterconnect structure in the M0 layer; and the location of thenon-recessed portion 112-2 might have been used to form a via structure(typically referred to as “VD”) to connect a source/drain interconnectstructure (typically referred to as “MD”) to an interconnect structurein the M0 layer. The source/drain interconnect structure MD (shown indotted line of FIG. 1) can be formed to couple a source/drain structure(e.g., the source/drain structure formed on one of the sides of the gatestructure 104) to an upper level of interconnect structure (e.g.,116-2). Such interconnect structures, e.g., VG, VD, MD, may becollectively referred to as middle-end-of-line (MEOL) structures. Insome embodiments, the combination of the recessed portion 112-1 and thenon-recessed portion 112-2 are sometimes referred to as “VG+VD.”

Referring still to FIG. 1, in greater detail, the recessed portion 112-1is recessed with respect to the non-recessed portion 112-2 to define arecess 113. In some embodiments, the recess 113 may be defined bymisalignment or displacement of respective top boundaries of therecessed portion 112-1 and the non-recessed portion 112-2. The recess113 is filled with a dielectric material to form a dielectric recessstructure 114. Each of the two portions 112-1 and 112-2 is directlyconnected to either the gate structure 104 or the interconnect structure116-2. For example, the recessed portion 112-1 is in direct contact withonly the gate structure 104; and the non-recessed portion 112-2 is indirect contact with only the interconnect structure 116-2. In some otherembodiments, the recessed portion 112-1 may be coupled to the gatestructure 104 with one or more conductive layers (e.g., a TaN layer)disposed therebetween. Similarly, the non-recessed portion 112-2 may becoupled to the interconnect structure 116-2 with one or more conductivelayers (e.g., a TaN layer) disposed therebetween.

By forming such a recessed interconnect structure 112, a connectionpoint (or via structure landing point) of the gate structure 104 can belaterally shifted from point “X” to point “Y,” as shown in FIG. 1. Thisallows the gate structure 104 to be electrically connected to theinterconnect structure 116-2 that is laterally displaced from the gatestructure 104. Further, by forming the dielectric recess structure 114over the recessed portion 112-1, the gate structure 104 can beelectrically isolated from any other interconnect structures (e.g.,116-1) but the interconnect structure 116-2. As such, a lateral width ofthe interconnect structure 116-2 can be formed to be sufficiently large,which can significantly reduce the possibility of failing in landinganother interconnect structure (e.g., a via structure connecting the M0layer 116 to the next upper interconnect layer, M1 layer, whichtypically referred to as “VIA0”) on the interconnect structure 116-2. Inthe existing technology, in order to connect the gate structures 102 and104 to the interconnect structures 116-1 and 116-2, respectively, atleast an end portion of the interconnect structure 116-2 is frequentlyformed to be vertically aligned with the gate structure 104, which cansignificantly shorten or squeeze the lateral width of the interconnectstructure 116-1. Accordingly, misalignment of the VIA0 may likely occur,which can fail in reaching the original functionality of thesemiconductor device 100.

Referring to FIG. 2, a cross-sectional view of a portion of asemiconductor device 200, including a recessed interconnect structure,is depicted, in accordance with some embodiments. It is understood thatthe semiconductor device 200, as shown in FIG. 2, is simplified forpurposes of illustration, and thus, the semiconductor device 200 caninclude any of various suitable features while remaining within thescope of the present disclosure. For example, the semiconductor device200 may include a plurality of transistors (e.g., planar complementarymetal-oxide-semiconductor field-effect transistors (planar MOSFETs),fin-based field-effect transistors (FinFETs), nanosheet field-effecttransistors, nanowire field-effect transistors, complementaryfield-effect transistors (CFETs)), each of which is formed by respectivegate structure and source/drain structures (or source/drain regions),while the illustrated embodiment of FIG. 2 includes some of thestructures.

As shown, the semiconductor device 200 includes a first gate structure202, a second gate structure 204, and a third gate structure 206 formedover a substrate (not shown). In some embodiments, the gate structures202-206 may include a conductive material such as, for example, one ormore metal materials, a polysilicon material, etc. Although not shown inFIG. 2, each of the gate structures 202-206 is formed over one or moreactive regions (e.g., one or more conduction channels) to modulate therespective transistor(s). For example, each of the gate structures202-206 may be formed over (e.g., to straddle) the active region of aFinFET to modulate current conducting through the FinFET.

The semiconductor device 200 further includes a number of source/draininterconnect structures (MDs) 212, 214, 216, and 218 over the substrate.Although not shown in FIG. 2, each of the MDs 212-218 is formed over anactive region (e.g., an epitaxially grown source/drain structure/region)to source or drain the respective transistor. For example, the MDs 212and 214 may be connected to the source structure and drain structure ofa first transistor, gated by the gate structure 202, to source and drainthe first transistor, respectively; the MDs 214 and 216 may be connectedto the source structure and drain structure of a second transistor,gated by the gate structure 204, to source and drain the secondtransistor, respectively; and the MDs 216 and 218 may be connected tothe source structure and drain structure of a third transistor, gated bythe gate structure 206, to source and drain the third transistor,respectively.

The gate structures 202-206 and MDs 212-218 are embedded in a dielectriclayer 208. The dielectric layer 208 may include a dielectric materialsuch as, for example, a low-k dielectric material, a ultra-low-kdielectric material. Such a dielectric layer 208 is typically referredto as an inter-layer dielectric (ILD) layer. Over the dielectric layer208, an interconnect structure 210 may be formed to connect one or moreof the gate structures 202-206 and/or the MDs 212-218. Similar as theinterconnect structure 116, a layer containing the interconnectstructure 210 is typically referred to as the M0 layer.

In certain cases, the second transistor, constituted by the gatestructure 204, the source/drain structures 214-216, may function as adummy transistor in the semiconductor device 200. The dummy transistormay have no active function during operation of the semiconductor device200. As such, the gate structure 204 and the source/drain structures214-216 can be connected to one another through an interconnectstructure 220. In this regard, the interconnect structure 220 mayinclude (or be coupled to) a recess, e.g., 221, according to someembodiments. The recess 221 is filled with a dielectric material to forma dielectric recess structure 222. The MD 212 can be electricallycoupled to the interconnect structure 210 through an interconnectstructure 232 (hereinafter “VD 232”) extending through the dielectriclayer 208; and the MD 218 can be electrically coupled to theinterconnect structure 210 through an interconnect structure 238(hereinafter “VD 238”) extending through the dielectric layer 208.

The interconnect structure 220 may be formed to include one or morerecessed portions 220-1, 220-2, and 220-3. As such, the interconnectstructure 220 may be referred to as a fully recessed interconnectstructure. In accordance with some embodiments, the recessed portion220-1 to 220-3 may be formed as respective via structures that areabutted (or otherwise adjacent) to each other. The location of therecessed portion 220-1 might have been used to form a VD to connect theMD 214 to the interconnect structure 210; the location of the recessedportion 220-2 might have been used to form a VG to connect the gatestructure 204 to the interconnect structure 210; and the location of therecessed portion 220-3 might have been used to form a VD to connect theMD 216 to the interconnect structure 210. In some embodiments, thecombination of the recessed portions 220-1 to 220-3 are sometimesreferred to as “VD+VG+VD.”

In the existing technology, the gate structure 204 and the source/drainstructures 214-216, which constitute a dummy transistor, are connectedto each other through a cut portion of the interconnect structure 210.Thus, in order to connect the MDs 212 and 218, at least one interconnectstructure in an interconnect layer next upper than the M0 layer (e.g.,an M1 layer) is required, which can significantly waste routing resourceat the M1 layer. In contrast, by forming the recessed interconnectstructure 220, a connection point of one or more interconnect structures(e.g., 220-1, 220-2, 220-3) can be vertically shifted from point “X” topoint “Y,” as shown in FIG. 2. This allows the MDs 212 and 218 to beconnected to each other directly through the interconnect structure 210,which can reserve the routing resource in the next upper interconnectlayer.

As discussed above, by forming the disclosed recessed interconnectstructure (e.g., 112 of FIG. 1) for connecting a FEOL conductivestructure (e.g., 104 of FIG. 1), a connection point of the FEOLconductive structure can be laterally shifted to allow a BEOLinterconnect structure corresponding to the FEOL to be laterally shiftedaccordingly. Consequently, the adjacent BEOL interconnect structure(s)can be formed to have a sufficiently large landing width. Thisalleviates various routing issues that the existing technology iscurrently facing, for example, when the dimension of a standard cell isincreasingly scaled down. Below are various example layout designs of acircuit that are constructed based on adopting the recessed interconnectstructure.

Referring first to FIG. 3, a circuit diagram of an example circuit 300is depicted. The circuit 300 includes an AND-OR-Invert (AOI) logiccircuit. The AOI logic circuit is generally constructed from thecombination of one or more AND gates followed by a NOR gate. As shown inFIG. 3, the circuit 300 has four inputs: A1, A2, B1, and B2; and oneoutput ZN that configured to perform the following Boolean function:(A1∧A2)∨(B1∧B2). To perform the function, the circuit 300 can includeeight transistors 302, 304, 306, 308, 310, 312, 314, and 316electrically coupled to one another. The transistors 302-308 can be eachimplemented as a p-type MOS transistor; and the transistors 310-316 canbe each implemented as an n-type MOS transistor. However, it isunderstood that each of the transistors 302-316 can be implemented asany of various other type of transistor.

In an embodiment, a drain of the transistors 302 is connected to asource of the transistor 304; and a drain of the transistors 306 isconnected to a source of the transistor 308. The transistor 302 is gatedby an interconnect structure configured to receive the input B1, andsourced by a first supply voltage (e.g., VDD); the transistor 304 isgated by an interconnect structure configured to receive the input A1,and drained to an interconnect structure configured to provide theoutput ZN; the transistor 306 is gated by an interconnect structureconfigured to receive the input B2, and sourced by the first supplyvoltage (e.g., VDD); and the transistor 308 is gated by an interconnectstructure configured to receive the input A2, and drained to theinterconnect structure configured to provide the output ZN. A drain ofthe transistors 310 is connected to the drain of the transistor 304 andalso drained to the interconnect structure configured to provide theoutput ZN; and a drain of the transistors 314 is connected to the drainof the transistor 308 and also drained to the interconnect structureconfigured to provide the output ZN. The transistor 310 is gated by theinterconnect structure configured to receive the input A1; and thetransistor 314 is gated by the interconnect structure configured toreceive the input B1. The source of the transistors 310 is connected toa drain of the transistor 312; and the source of the transistors 314 isconnected to a drain of the transistor 316. The transistor 312 is gatedby the interconnect structure configured to receive the input A2, andsourced by a second supply voltage (e.g., VSS); and the transistor 316is gated by the interconnect structure configured to receive the inputB2, and sourced by the second supply voltage (e.g., VSS).

Referring to FIG. 4, an example layout design 400 of a standard cell isdepicted, in accordance with some embodiments. The layout design 400 maybe used to fabricate at least a portion of a semiconductor device (e.g.,500 in FIG. 5) functioning as the circuit 300 of FIG. 3. By adopting therecessed interconnect structures disclosed herein, the dimension (e.g.,area) of the layout design 400 (or the standard cell) can be scaled downwhile being immune from the above-identified routing issues. Forexample, a cell width of the standard cell may be reduced to beingproportional to a relatively low number of gate structures (e.g., 5 orless gate structure spaces), and a cell height of the standard cell maybe reduced to being proportional to a relatively low number of signaltracks (e.g., 3 or less M0 interconnect structure spaces).

The semiconductor device corresponding to the layout design 400 may befabricated based on forming the respective active feature of thetransistors 302-316 along a single level of active regions. Such anactive region may be a fin-shaped region of one or morethree-dimensional field-effect-transistors (e.g., FinFETs,gate-all-around (GAA) transistors including nanosheet transistors andnanowire transistors), or an oxide-definition (OD) region of one or moreplanar metal-oxide-semiconductor field-effect-transistors (MOSFETs),wherein the active region may serve as a source feature or drain featureof the respective transistor(s). The term “single level” of multipleactive regions may be referred to as the active regions being formedalong a single lateral plane, in some embodiments of the presentdisclosure.

In FIG. 4, the layout design 400 includes patterns 402 and 404. Thepatterns 402 and 404 may extend along the X direction, that areconfigured to form active regions over a substrate, hereinafter “activeregion 402” and “active region 404,” respectively. The active region 402may be characterized with a first conduction type, and the active region404 may be characterized with a second conduction type. For example, theactive region 402 includes a p-type doped region, and the active region404 includes an n-type doped region. The layout design 400 can be usedto form the transistors 302-316 in various configurations. In oneexample where the transistors 302-316 are to be formed as FinFETs, theactive region 402 may be formed as a p-type fin-based structure over asubstrate, and the active region 404 may be formed as an n-typefin-based structure over the substrate. In another example where thetransistor 302-316 are to be formed as nanosheet transistors, the activeregion 402 may be formed as one or more p-type nanosheets stacked on topof one another over a substrate, and the active region 404 may be formedas one or more n-type nanosheets stacked on top of one another over thesubstrate. In yet another example where the transistors 302-316 are tobe formed as planar MOSFETs, the active region 402 may be formed as ap-type region recessed in a substrate, and the active region 404 may beformed as an n-type region recessed in the substrate.

The layout design 400 includes patterns 406, 408, 410, 412, 414, and416. The patterns 406, 408, 410, 412, 414, and 416 may extend along theY direction, that are configured to form gate structures, hereinafter“gate structure 406,” “gate structure 408,” “gate structure 410,” “gatestructure 412,” “gate structure 414,” and “gate structure 416,”respectively. The gate structure 406 may be disposed along or over afirst boundary of the layout design 400 (or the cell), and the gatestructure 416 may be disposed along or over a second boundary of thelayout design 400 (or the cell). The gate structures 406 and 416 may notprovide an electrical or conductive path, and may prevent or at leastreduce/minimize current leakage across components between which the gatestructures 406 and 416 are located. The gate structures 406 and 416 caninclude dummy polysilicon lines, which are sometimes referred to asPODEs. Each of the remaining gate structures 408-414, formed of one ormore conductive materials (e.g., polysilicon(s), metal(s)), can overlayrespective portions of the active regions 402 and 404 to define one ofthe transistors 302-316.

For example, the portion of the gate structure 408 that overlays theactive region 402 can define the gate of the transistor 308, and theportions of the active region 402 that are disposed on the left-handside and right-hand side of the gate structure 408 can define the sourceand drain of the transistor 308, respectively. The portion of the gatestructure 410 that overlays the active region 402 can define the gate ofthe transistor 304, and the portions of the active region 402 that aredisposed on the left-hand side and right-hand side of the gate structure410 can define the drain and source of the transistor 304, respectively.The portion of the gate structure 412 that overlays the active region402 can define the gate of the transistor 302, and the portions of theactive region 402 that are disposed on the left-hand side and right-handside of the gate structure 412 can define the drain and source of thetransistor 302, respectively. The portion of the gate structure 414 thatoverlays the active region 402 can define the gate of the transistor306, and the portions of the active region 402 that are disposed on theleft-hand side and right-hand side of the gate structure 414 can definethe source and drain of the transistor 306, respectively. The portion ofthe gate structure 408 that overlays the active region 404 can definethe gate of the transistor 312, and the portions of the active region404 that are disposed on the left-hand side and right-hand side of thegate structure 408 can define the source and drain of the transistor312, respectively. The portion of the gate structure 410 that overlaysthe active region 404 can define the gate of the transistor 310, and theportions of the active region 404 that are disposed on the left-handside and right-hand side of the gate structure 410 can define the sourceand drain of the transistor 310, respectively. The portion of the gatestructure 412 that overlays the active region 404 can define the gate ofthe transistor 314, and the portions of the active region 404 that aredisposed on the left-hand side and right-hand side of the gate structure412 can define the drain and source of the transistor 314, respectively.The portion of the gate structure 414 that overlays the active region404 can define the gate of the transistor 316, and the portions of theactive region 404 that are disposed on the left-hand side and right-handside of the gate structure 414 can define the drain and source of thetransistor 316, respectively.

The layout design 400 includes patterns 420, 422, 424, 426, 428, 430,432, 434, and 436. The patterns 420, 422, 424, 426, 428, 430, 432, 434,and 436 may extend along the Y direction, that are configured to formsource/drain interconnect structures (e.g., MDs), hereinafter “MD 420,”“MD 422,” “MD 424,” “MD 426,” “MD 428,” “MD 430,” “MD 432,” “MD 434,”and “MD 436.” Each of the MDs 420-436 may electrically couple the sourceor drain of a corresponding transistor to an interconnect structurethrough a via interconnect structure.

The layout design 400 includes patterns 440, 442, 444, 446, 448, 450,452, 454, and 456. The patterns 440, 442, 444, 446, 448, 450, 452, 454,and 456 may be configured to form via interconnect structures (e.g.,VDs), hereinafter “VD 440,” “VD 442,” “VD 444,” “VD 446,” “VD 448,” “VD450,” “VD 452,” “VD 454,” and “VD 456.” Each of the VDs 440-456, exceptfor the VD 452, may extend along a vertical direction (e.g., a directionperpendicular to the X direction and the Y direction) by a respectiveheight in order to electrically couple a corresponding MD to aninterconnect structure.

The layout design 400 includes patterns 458, 460, 462, and 464. Thepatterns 458, 460, 462, and 464 may be configured to form viainterconnect structures (e.g., VGs), hereinafter “VG 458,” “VG 460,” “VG462,” and “VG 464.” Each of the VGs 458-464, except for the VG 460, mayextend along a vertical direction (e.g., a direction perpendicular tothe X direction and the Y direction) by a respective height in order tocouple a corresponding gate structure to an interconnect structure. Insome embodiments, the patterns 452 and 460 may be partially overlappedwith each other to form a combination of VD and VG, hereinafter “VD+VG491.” Further, the layout design 400 includes a pattern 461 overlappingrespective portions of the pattern 452 and 460 to form a dielectricrecess structure (hereinafter “recess 461”) by filling a recessed upperportion of the VD+VG 491 with a dielectric material.

The layout design 400 includes patterns 470, 472, 474, 476, and 478. Thepatterns 470, 472, 474, 476, and 478 may extend along the X direction,that are configured to form interconnect structures (e.g., M0 signaltracks or power rails) over the substrate, hereinafter “power rail 470,”“M0 track 472,” “M0 track 474,” “M0 track 476” and “power rail 478,”respectively. In some embodiments, the power rail 470, disposed along orover a third boundary of the layout design (cell), may be configured tocarry a first supply voltage (e.g., VDD); and the power rail 478,disposed along or over a fourth boundary of the layout design (cell),may be configured to carry a second supply voltage (e.g., VSS). Toconnect the transistors 302-316 as shown in FIG. 3, some of the M0tracks may be “cut” into a plurality of portions by one or more M0 cutpatterns. For example, the M0 track 474 may be cut into M0 trackportions 474-1 and 474-2 by a cut pattern 465 (hereinafter “cut M0465”); and the M0 track 476 may be cut into M0 track portions 476-1,476-2, and 476-3 by a cut pattern 467 (hereinafter “cut M0 467”) and acut pattern 463 (hereinafter “cut M0 463”), respectively. In someembodiments, the cut M0 s 463, 465, and 467 may be filled or refilledwith a dielectric material to electrically isolate corresponding M0track portions from each other.

The correspondence between the layout design 400 (FIG. 4) and thecircuit 300 (FIG. 3) can be further illustrated through the followingdiscussion. For example, both of the portion of the active region 402 onthe right-hand side of the gate structure 412 (the source of thetransistor 302) and the portion of the active region 402 on theleft-hand side of the gate structure 414 (the source of the transistor306) are electrically coupled to the power rail 470 (VDD) by the MD 426and VD 446. Both of the portion of the active region 404 on theright-hand side of the gate structure 410 (the drain of the transistor310) and the portion of the active region 404 on the left-hand side ofthe gate structure 412 (the drain of the transistor 314) areelectrically coupled to the M0 signal track 474, which can be connectedto an interconnect structure configured to provide the output ZN that isdisposed at the next upper interconnect layer (e.g., M1 layer), by theMD 432 and VD 454. The portion of the active region 404 on the left-handside of the gate structure 408 (the source of the transistor 312) iselectrically coupled to VSS (the power rail 478) by the MD 436 and VD456.

Referring to FIG. 5, a cross-sectional view of a portion of theabove-mentioned semiconductor device 500, made according to the layoutdesign 400, is depicted, in accordance with some embodiments. It isunderstood that the semiconductor device 500 shown in FIG. 5 is not acompleted semiconductor device functioning as the circuit 300 (FIG. 3).For example, the cross-sectional view in FIG. 5 depicts a portion of thesemiconductor device 500 that is made according to the portion 400′ ofthe layout design. As shown in FIG. 5, the gate structures 410, 412, and414 are disposed over the active region 404 to form the transistor 310'sgate, the transistor's 314's gate, and the transistor's 316's gate,respectively, with the transistor 310's source (hereinafter“source/drain region 502”), the transistor 310's drain and transistor314's drain (hereinafter “source/drain region 504”) and transistor 314'ssource and transistor 316's drain (hereinafter “source/drain region506”) formed in the active region 404. Corresponding to the layoutdesign 400′ of FIG. 4, the MD 434, connected to the source/drain region502, is disposed on the left-hand side of the gate structure 410. The MD434 may be vertically aligned with the cut M0 467. The gate structure410 is connected to the M0 track portion 476-2 through the VG 462. TheMD 432, connected to the source/drain region 504, is disposed on theright-hand side of the gate structure 410 but not connected to the M0track portion 476-2. The gate structure 412 is connected to the M0 trackportion 476-3 through the combination of VG 460 and VD 452 (VD+VG 491)with the recess 461 filling an upper portion of the combination of theVD+VG 491. In some embodiments, at least a portion of the recess 461 isvertically aligned with the cut M0 463 (filled with a dielectricmaterial) and the gate structure 412. As such, the gate structure 412can be electrically coupled to the M0 track portion 476-3 whileelectrically isolated from one or more other M0 track portions (e.g.,476-2). Further, the VD+VG 491 is electrically isolated from thesource/drain region 506 by a dielectric feature 508.

By recessing the VD+VG 491, a connection point of the gate structure 412can be laterally shifted from approximately where the gate structure 412is formed to approximately where the source/drain region 506 is formed.The cut M0 463 can be accordingly shifted from approximately where theMD 432 is formed to approximately where the gate structure 412 isformed. As such, a lateral width “W” of the M0 track portion 476-2 shallnot be squeezed. In some embodiments, the width W can be maintained atleast 1.5 times a distance “d” between adjacent ones of the gatestructures (e.g., between 410 and 412).

Referring again to FIG. 4, the layout design 400 includes patterns 481,483, 485, 487, and 489. The patterns 481, 483, 485, 487, and 489 may beconfigured to form via interconnect structures (e.g., VIA0) over therespective M0 tracks, hereinafter “VIA0 481,” “VIA0 483,” “VIA0 485,”“VIA0 487” and “VIA0 489,” respectively. Each of the VIA0 s 481-489 mayextend along a vertical direction (e.g., a direction perpendicular tothe X direction and the Y direction) by a respective height in order toelectrically couple a corresponding M0 track to an interconnectstructure at the next upper interconnect layer (e.g., M1 layer).

The layout design 400 includes patterns 480, 482, 484, 486, and 488. Thepatterns 480, 482, 484, 486, and 488 may be configured to forminterconnect structures (e.g., M1 tracks) at the next upper interconnectlayer M1, hereinafter “M1 track 480,” “M1 track 482,” “M1 track 484,”“M1 track 486” and “M1 track 488,” respectively. Each of the M1 tracks480-488 may be configured to either receive one of the inputs A1, A2,B1, and B2 (FIG. 3), or provide the output ZN (FIG. 3). For example, theM1 track 480 is configured for receiving the input B2. From the M1 track480, through the VIA0 481, further through the M0 track 474, and thenthrough the VG 458, the input B2 can be coupled to the gate structure414 (the gates of the transistors 306 and 316). In another example, theM1 track 482 is configured for receiving the input B1. From the M1 track482, further through the M0 track 476, and then through the VD+VG 491,the input B1 can be coupled to the gate structure 412 (the gates of thetransistors 302 and 314).

Referring to FIGS. 6A and 6B, example layout designs 600A and 600B of astandard cell are respectively depicted, in accordance with someembodiments. The layout designs 600A and 600B may be used to fabricateat least a portion of a semiconductor device (e.g., 700 in FIG. 7)functioning as the circuit 300 of FIG. 3. By adopting the recessedinterconnect structures disclosed herein, the dimension (e.g., area) ofthe layout designs 600A and 600B (or the standard cells) can be scaleddown while being immune from the above-identified routing issues. Forexample, a cell width of the standard cell may be reduced to beingproportional to a relatively low number of gate structures (e.g., 5 orless gate structure spaces), and a cell height of the standard cell maybe reduced to being proportional to a relatively low number of signaltracks (e.g., 3 or less M0 interconnect structure spaces).

The semiconductor device corresponding to the layout designs 600A and600B may be fabricated based on forming the respective active feature ofthe transistors 302-308, having a first conduction type, along a firstlevel of active regions, and the respective active feature of thetransistors 310-316, having a second conduction type, along a secondlevel of active regions. The first level and the second level may bevertically aligned with each other. The structure/configuration to placedifferent conduction types of transistors at two vertically alignedlevels is sometimes referred to as a complementary field-effecttransistor (CFET) configuration. In some embodiments, power rails ofsuch a CFET can be disposed either above the upper level where one ofthe first or second conduction types of transistors are formed, or belowthe lower level where the other of the first or second conduction typesof transistors are formed. When placing the power rails below the lowerlevel, the CFET is typically referred to as a CFET with buried power. Byburying the power rails, the area (e.g., the cell height) of acorresponding cell can be further reduced, for example, by about 30˜40%.The semiconductor device 700, as shown in FIG. 7, provides an example ofsuch a CFET having buried power.

FIG. 7 provides a perspective view of the semiconductor device 700, madebased on the layout designs 600A and 600B, in accordance with someembodiments. Accordingly, the layout designs 600A and 600B shall bediscussed in conjunction with FIG. 7. It is understood that thesemiconductor device 700 of FIG. 7 has been simplified for purposes ofillustration, and thus, some of the features/regions/structures includedin the layout designs 600A and 600B may not be shown in FIG. 7.

In FIG. 6A, the layout design 600A includes pattern 604. The pattern 604may extend along the X direction, that is configured to form an activeregion over a substrate at a lower level, hereinafter “active region604.” The active region 604 may be characterized with a first conductiontype. For example, the active region 604 includes an n-type dopedregion. The active region 604 can form the transistors 310-316 invarious configurations such as, for example, FinFETs, nanosheettransistors, etc.

The layout design 600A includes patterns 612, 614, 616, 618, 620, and622. The patterns 612, 614, 616, 618, 620, and 622 may extend along theY direction, that are configured to form gate structures at the lowerlevel, hereinafter “gate structure 612,” “gate structure 614,” “gatestructure 616,” “gate structure 618,” “gate structure 620,” and “gatestructure 622,” respectively. The gate structure 612 may be disposedalong or over a first boundary of the layout design 600A (or the cell),and the gate structure 622 may be disposed along or over a secondboundary of the layout design 600A (or the cell). The gate structures612 and 622 may not provide an electrical or conductive path, and mayprevent or at least reduce/minimize current leakage across componentsbetween which the gate structures 612 and 622 are located. The gatestructures 612 and 622 can include dummy polysilicon lines, which aresometimes referred to as PODEs. Each of the remaining gate structures614-620, formed of one or more conductive materials (e.g.,polysilicon(s), metal(s)), can overlay respective portions of the activeregion 604 to define one of the transistors 310-316.

For example, the portion of the gate structure 614 that overlays theactive region 604 can define the gate of the transistor 316, and theportions of the active region 604 that are disposed on the left-handside and right-hand side of the gate structure 614 can define the sourceand drain of the transistor 316, respectively. The portion of the gatestructure 616 that overlays the active region 604 can define the gate ofthe transistor 314, and the portions of the active region 604 that aredisposed on the left-hand side and right-hand side of the gate structure616 can define the source and drain of the transistor 314, respectively.The portion of the gate structure 618 that overlays the active region604 can define the gate of the transistor 310, and the portions of theactive region 604 that are disposed on the left-hand side and right-handside of the gate structure 618 can define the drain and source of thetransistor 310, respectively. The portion of the gate structure 620 thatoverlays the active region 604 can define the gate of the transistor312, and the portions of the active region 604 that are disposed on theleft-hand side and right-hand side of the gate structure 620 can definethe source and drain of the transistor 312, respectively.

The layout design 600A includes patterns 601 and 603. The patterns 601and 603 may extend along the X direction, that are configured to formpower rails over the substrate, hereinafter “power rail 601” and “powerrail 603,” respectively. In some embodiments, the power rail 601,disposed along a third boundary of the layout design (cell), may beconfigured to carry a first supply voltage (e.g., VDD); and the powerrail 603, disposed along a fourth boundary of the layout design (cell),may be configured to carry a second supply voltage (e.g., VSS). In someembodiments, the power rails 601 and 603 may be disposed below theactive region 604.

The layout design 600A includes patterns 624, 626, 628, 630, and 632.The patterns 624, 626, 628, 630, and 632 may extend along the Ydirection, that are configured to form source/drain interconnectstructures (e.g., MDs) at the lower level, hereinafter “MD 624,” “MD626,” “MD 628,” “MD 630,” and “MD 632.” Each of the MDs 624, 628, and632 may electrically couple the source or drain of a correspondingtransistor to an interconnect structure through a via interconnectstructure.

The layout design 600A includes patterns 634, 636, 638, and 640. Thepatterns 634, 636, 638, and 640 may be configured to form viainterconnect structures (e.g., VDs), hereinafter “VD 634,” “VD 636,” “VD638,” and “VD 640.” Each of the VDs 634-640 may extend along a verticaldirection (e.g., a direction perpendicular to the X direction and the Ydirection) by a respective height in order to electrically couple acorresponding MD to an interconnect structure, or a power rail. Forexample in the perspective view of FIG. 7, the VD 634 can verticallyextend (e.g., along the Z direction) to electrically couple the MD 624to the power rail 603 (not shown in FIG. 7); the VD 638 can verticallyextend (e.g., along the Z direction) to electrically couple the powerrail 601 (not shown in FIG. 7) to an interconnect structure (e.g., MD662) at the upper level; and the VD 636 can vertically extend (e.g.,along the Z direction) to electrically couple the MD 632 to the powerrail 603 (not shown in FIG. 7).

In FIG. 6B, the layout design 600B includes pattern 644. The pattern 644may extend along the X direction, that is configured to form an activeregion over a substrate at an upper level, hereinafter “active region644.” The active region 644 may be characterized with a secondconduction type. For example, the active region 644 includes a p-typedoped region. The active region 644 can form the transistors 302-308 invarious configurations such as, for example, FinFETs, nanosheettransistors, etc.

The layout design 600B includes patterns 646, 648, 650, 652, 654, and656. The patterns 646, 648, 650, 652, 654, and 656 may extend along theY direction, that are configured to form gate structures at the upperlevel, hereinafter “gate structure 646,” “gate structure 648,” “gatestructure 650,” “gate structure 652,” “gate structure 654,” and “gatestructure 656,” respectively. In some embodiments, the gate structures646, 648, 650, 652, 654, and 656 may be vertically aligned with (and/orelectrically coupled to) the gate structures 612, 614, 616, 618, 620,and 622, respectively, as illustrated in FIG. 7. In some embodiments,the gate structures 646, 648, 650, 652, 654, and 656 may be integrallymerged with the gate structures 612, 614, 616, 618, 620, and 622,respectively. Thus, the gate structures 646 and 656 can be formed asPODEs. Each of the remaining gate structures 648-654, formed of one ormore conductive materials (e.g., polysilicon(s), metal(s)), can overlayrespective portions of the active region 644 to define one of thetransistors 302-308.

For example, the portion of the gate structure 648 that overlays theactive region 644 can define the gate of the transistor 306, and theportions of the active region 644 that are disposed on the left-handside and right-hand side of the gate structure 648 can define the drainand source of the transistor 306, respectively. The portion of the gatestructure 650 that overlays the active region 644 can define the gate ofthe transistor 302, and the portions of the active region 644 that aredisposed on the left-hand side and right-hand side of the gate structure650 can define the source and drain of the transistor 314, respectively.The portion of the gate structure 652 that overlays the active region644 can define the gate of the transistor 304, and the portions of theactive region 644 that are disposed on the left-hand side and right-handside of the gate structure 652 can define the source and drain of thetransistor 304, respectively. The portion of the gate structure 654 thatoverlays the active region 644 can define the gate of the transistor308, and the portions of the active region 644 that are disposed on theleft-hand side and right-hand side of the gate structure 654 can definethe drain and source of the transistor 308, respectively.

The layout design 600B includes patterns 660, 662, 664, 666, and 668.The patterns 660, 662, 664, 666, and 668 may extend along the Ydirection, that are configured to form source/drain interconnectstructures (e.g., MDs) at the upper level, hereinafter “MD 660,” “MD662,” “MD 664,” “MD 666,” and “MD 668.” Each of the MDs 660, 662, 664,666, and 668 may electrically couple the source or drain of acorresponding transistor to an interconnect structure through a viainterconnect structure.

The layout design 600B includes patterns 670, 672, 674, 676, and 678.The patterns 670, 672, 674, 676, and 678 may be configured to form viainterconnect structures (e.g., VDs), hereinafter “VD 670,” “VD 672,” “VD674,” “VD 676,” and “VD 678.” Each of the VDs 670-678, except for the VD672, may extend along a vertical direction (e.g., a directionperpendicular to the X direction and the Y direction) by a respectiveheight in order to electrically couple a corresponding MD to aninterconnect structure.

The layout design 600B includes patterns 680, 682, 684, and 686. Thepatterns 680, 682, 684, and 686 may be configured to form viainterconnect structures (e.g., VGs), hereinafter “VG 680,” “VG 682,” “VG684,” and “VG 686.” Each of the VGs 680-686, except for the VG 682, mayextend along a vertical direction (e.g., a direction perpendicular tothe X direction and the Y direction) by a respective height in order tocouple a corresponding gate structure to an interconnect structure. Insome embodiments, the patterns 672 and 682 may be partially overlappedwith each other to form a combination of VD and VG, hereinafter “VD+VG691.” Further, the layout design 600B includes a pattern 661 overlappingrespective portions of the pattern 672 and 682 to form a dielectricrecess structure (hereinafter “recess 661”) by filling a recessed upperportion of the VD+VG 691 with a dielectric material.

The layout design 600B includes patterns 688, 689, and 690. The patterns688, 689, and 690 may extend along the X direction, that are configuredto form interconnect structures (e.g., M0 signal tracks) over the activeregion 644, hereinafter “M0 track 688,” “M0 track 689,” and “M0 track690,” respectively. To connect the transistors 302-316 as shown in FIG.3, some of the M0 tracks may be “cut” into a plurality of portions byone or more M0 cut patterns. For example, the M0 track 688 may be cutinto M0 track portions 688-1 and 688-2 by a cut pattern 693 (hereinafter“cut M0 693”); the M0 track 690 may be cut into M0 track portions 690-1,690-2, and 690-3 by the same cut M0 693 and a cut pattern 694(hereinafter “cut M0 694”), respectively. In some embodiments, the cutM0 s 693 and 694 may be filled or refilled with a dielectric material toelectrically isolate corresponding M0 track portions from each other.

The correspondence between the layout design 600A and 600B (FIGS. 6A and6B) and the circuit 300 (FIG. 3) can be further illustrated through thediscussion of semiconductor device 700 of FIG. 7, as follows. Forexample, the gate structure 650 (the gate of the transistor 302) iselectrically coupled to the M0 track portion 690-1 through the VD+VG691. The gate structure 652 (the gate of the transistor 304) iselectrically coupled to the M0 track portion 690-2 through the VG 684.As yet another representative example, the gate structure 654 (the gateof the transistor 308) is electrically coupled to the M0 track portion690-3 through the VG 686. The gate structure 648 (the gate of thetransistor 306) is electrically coupled to the M0 track portions 688-1through the VG 680. Both of the portion of the active region 644 on theright-hand side of the gate structure 652 (the drain of the transistor304) and the portion of the active region 644 on the left-hand side ofthe gate structure 654 (the drain of the transistor 308) areelectrically coupled to the M0 track portion 688-2 through the MD 666and VD 676. Both of the portion of the active region 604 on theright-hand side of the gate structure 616 (the drain of the transistor314) and the portion of the active region 604 on the left-hand side ofthe gate structure 618 (the drain of the transistor 310) areelectrically coupled to the M0 track portion 688-2 through the MD 628and VD 640.

In some embodiments, by recessing the VD+VG 691, a connection point ofthe gate structure 650 can be laterally shifted from approximately wherethe gate structure 650 is formed to approximately where the source ofthe transistor 302 (on the left-hand side of the gate structure 650) isformed. The cut M0 693 can be accordingly shifted from approximatelywhere the MD 662 is formed to approximately where the gate structure 650is formed. As such, a lateral width of the M0 track portion 690-2 shallnot be squeezed, and can be characterized with a sufficiently largelanding width (e.g., equal to or greater than 1.5 times a distancebetween adjacent ones of the gate structures).

Referring again to FIG. 6B, the layout design 600B includes patterns671, 673, 675, 677, and 679. The patterns 671, 673, 675, 677, and 679may be configured to form via interconnect structures (e.g., VIA0) overthe respective M0 tracks, hereinafter “VIA0 671,” “VIA0 673,” “VIA0675,” “VIA0 677” and “VIA0 679,” respectively. Each of the VIA0 s 671,673, 675, 677, and 679 may extend along a vertical direction (e.g., adirection perpendicular to the X direction and the Y direction) by arespective height in order to electrically couple a corresponding M0track to an interconnect structure at the next upper interconnect layer(e.g., M1 layer).

The layout design 600B includes patterns 681, 683, 685, 687, and 689′.The patterns 681, 683, 685, 687, and 689′ may be configured to forminterconnect structures (e.g., M1 tracks) at the next upper interconnectlayer M1, hereinafter “M1 track 681,” “M1 track 683,” “M1 track 685,”“M1 track 687” and “M1 track 689′,” respectively. Each of the M1 tracks681, 683, 685, 687, and 689′ may be configured to either receive one ofthe inputs A1, A2, B1, and B2 (FIG. 3), or provide the output ZN (FIG.3). For example, the M1 track 683 is configured for receiving the inputB2. From the M1 track 683, through the VIAO 673, further through the M0track 688, and then through the VG 680, the input B2 can be coupled tothe gate structure 648 (the gate of the transistor 306) and the gatestructure 614 (the gate of the transistor 316). In another example, theM1 track 681 is configured for receiving the input B1. From the M1 track681 and through the VD+VG 691, the input B1 can be coupled to the gatestructure 650 (the gate of the transistor 302) and the gate structure616 (the gate of the transistor 314).

FIG. 8 is a flowchart of a method 800 of forming or manufacturing asemiconductor device, in accordance with some embodiments. It isunderstood that additional operations may be performed before, during,and/or after the method 800 depicted in FIG. 8. In some embodiments, themethod 800 is usable to form a semiconductor device, according tovarious layout designs as disclosed herein.

In operation 810 of the method 800, a layout design of a semiconductordevice is generated. The operation 810 is performed by a processingdevice (e.g., processor 902 (FIG. 9)) configured to execute instructionsfor generating a layout design. In one approach, the layout design isgenerated by placing layout designs of one or more standard cellsthrough a user interface. In one approach, the layout design isautomatically generated by a processor executing a synthesis tool thatconverts a logic design (e.g., Verilog) into a corresponding layoutdesign. In some embodiments, the layout design is rendered in a graphicdatabase system (GDSII) file format.

In operation 820 of the method 800, the a semiconductor device ismanufactured based on the layout design. In some embodiments, theoperation 820 of the method 800 comprises manufacturing at least onemask based on the layout design, and manufacturing the a semiconductordevice based on the at least one mask. A number of example manufacturingoperations of the operation 820 shall be discussed with respect to themethod 1100 of FIG. 11 below.

FIG. 9 is a schematic view of a system 900 for designing andmanufacturing an IC layout design, in accordance with some embodiments.System 900 generates or places one or more IC layout designs describedherein. In some embodiments, the system 900 manufactures one or moresemiconductor devices based on the one or more IC layout designsdescribed herein. The system 900 includes a hardware processor 902 and anon-transitory, computer readable storage medium 904 encoded with, e.g.,storing, the computer program code 906, e.g., a set of executableinstructions. Computer readable storage medium 904 is configured forinterfacing with manufacturing machines for producing the semiconductordevice. The processor 902 is electrically coupled to the computerreadable storage medium 904 by a bus 908. The processor 902 is alsoelectrically coupled to an I/O interface 910 by bus 908. A networkinterface 912 is also electrically connected to the processor 902 by bus908. Network interface 912 is connected to a network 914, so thatprocessor 902 and computer readable storage medium 904 are capable ofconnecting to external elements via network 914. The processor 902 isconfigured to execute the computer program code 906 encoded in thecomputer readable storage medium 904 in order to cause system 900 to beusable for performing a portion or all of the operations as described inmethod 800.

In some embodiments, the processor 902 is a central processing unit(CPU), a multi-processor, a distributed processing system, anapplication specific integrated circuit (ASIC), and/or a suitableprocessing unit.

In some embodiments, the computer readable storage medium 904 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example, the computerreadable storage medium 904 includes a semiconductor or solid-statememory, a magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk, and/or anoptical disk. In some embodiments using optical disks, the computerreadable storage medium 904 includes a compact disk-read only memory(CD-ROM), a compact disk-read/write (CD-R/W), and/or a digital videodisc (DVD).

In some embodiments, the computer readable storage medium 904 stores thecomputer program code 906 configured to cause system 900 to performmethod 800. In some embodiments, the computer readable storage medium904 also stores information needed for performing method 800 as well asinformation generated during performance of method 800, such as layoutdesign 916, user interface 918, fabrication unit 920, and/or a set ofexecutable instructions to perform the operation of method 800.

In some embodiments, the computer readable storage medium 904 storesinstructions (e.g., computer program code 906) for interfacing withmanufacturing machines. The instructions (e.g., computer program code906) enable processor 902 to generate manufacturing instructionsreadable by the manufacturing machines to effectively implement method800 during a manufacturing process.

System 900 includes I/O interface 910. I/O interface 910 is coupled toexternal circuitry. In some embodiments, I/O interface 910 includes akeyboard, keypad, mouse, trackball, trackpad, and/or cursor directionkeys for communicating information and commands to processor 902.

System 900 also includes network interface 912 coupled to the processor902. Network interface 912 allows system 900 to communicate with network914, to which one or more other computer systems are connected. Networkinterface 912 includes wireless network interfaces such as BLUETOOTH,WIFI, WIMAX, GPRS, or WCDMA; or wired network interface such asETHERNET, USB, or IEEE-13154. In some embodiments, method 800 isimplemented in two or more systems 900, and information such as layoutdesign, user interface and fabrication unit are exchanged betweendifferent systems 900 by network 914.

System 900 is configured to receive information related to a layoutdesign through I/O interface 910 or network interface 912. Theinformation is transferred to processor 902 by bus 908 to determine alayout design for producing an IC. The layout design is then stored incomputer readable storage medium 904 as layout design 916. System 900 isconfigured to receive information related to a user interface throughI/O interface 910 or network interface 912. The information is stored incomputer readable storage medium 904 as user interface 918. System 900is configured to receive information related to a fabrication unitthrough I/O interface 910 or network interface 912. The information isstored in computer readable storage medium 904 as fabrication unit 920.In some embodiments, the fabrication unit 920 includes fabricationinformation utilized by system 900.

In some embodiments, method 800 is implemented as a standalone softwareapplication for execution by a processor. In some embodiments, method800 is implemented as a software application that is a part of anadditional software application. In some embodiments, method 800 isimplemented as a plug-in to a software application. In some embodiments,method 800 is implemented as a software application that is a portion ofan EDA tool. In some embodiments, method 800 is implemented as asoftware application that is used by an EDA tool. In some embodiments,the EDA tool is used to generate a layout design of the integratedcircuit device. In some embodiments, the layout design is stored on anon-transitory computer readable medium. In some embodiments, the layoutdesign is generated using a tool such as VIRTUOSO® available fromCADENCE DESIGN SYSTEMS, Inc., or another suitable layout generatingtool. In some embodiments, the layout design is generated based on anetlist which is created based on the schematic design. In someembodiments, method 800 is implemented by a manufacturing device tomanufacture an integrated circuit using a set of masks manufacturedbased on one or more layout designs generated by system 900. In someembodiments, system 900 includes a manufacturing device (e.g.,fabrication unit 920) to manufacture an integrated circuit using a setof masks manufactured based on one or more layout designs of the presentdisclosure. In some embodiments, system 900 of FIG. 9 generates layoutdesigns of an IC that are smaller than other approaches. In someembodiments, system 900 of FIG. 9 generates layout designs of asemiconductor device that occupy less area than other approaches.

FIG. 10 is a block diagram of an integrated circuit (IC)/semiconductordevice manufacturing system 1000, and an IC manufacturing flowassociated therewith, in accordance with at least one embodiment of thepresent disclosure.

In FIG. 10, IC manufacturing system 1000 includes entities, such as adesign house 1020, a mask house 1030, and an IC manufacturer/fabricator(“fab”) 1040, that interact with one another in the design, development,and manufacturing cycles and/or services related to manufacturing an ICdevice 1060. The entities in system 1000 are connected by acommunications network. In some embodiments, the communications networkis a single network. In some embodiments, the communications network isa variety of different networks, such as an intranet and the Internet.The communications network includes wired and/or wireless communicationchannels. Each entity interacts with one or more of the other entitiesand provides services to and/or receives services from one or more ofthe other entities. In some embodiments, two or more of design house1020, mask house 1030, and IC fab 1040 is owned by a single company. Insome embodiments, two or more of design house 1020, mask house 1030, andIC fab 1040 coexist in a common facility and use common resources.

Design house (or design team) 1020 generates an IC design layout 1022.IC design layout 1022 includes various geometrical patterns designed foran IC device 1060. The geometrical patterns correspond to patterns ofmetal, oxide, or semiconductor layers that make up the variouscomponents of IC device 1060 to be fabricated. The various layerscombine to form various IC features. For example, a portion of IC designlayout 1022 includes various IC features, such as an active region, gateelectrode, source electrode and drain electrode, metal lines or viacontacts of an interlayer interconnection, and openings for bondingpads, to be formed in a semiconductor substrate (such as a siliconwafer) and various material layers disposed on the semiconductorsubstrate. Design house 1020 implements a proper design procedure toform IC design layout 1022. The design procedure includes one or more oflogic design, physical design or place and route. IC design layout 1022is presented in one or more data files having information of thegeometrical patterns. For example, IC design layout 1022 can beexpressed in a GDSII file format or DFII file format.

Mask house 1030 includes mask data preparation 1032 and mask fabrication1034. Mask house 1030 uses IC design layout 1022 to manufacture one ormore masks to be used for fabricating the various layers of IC device1060 according to IC design layout 1022. Mask house 1030 performs maskdata preparation 1032, where IC design layout 1022 is translated into arepresentative data file (“RDF”). Mask data preparation 1032 providesthe RDF to mask fabrication 1034. Mask fabrication 1034 includes a maskwriter. A mask writer converts the RDF to an image on a substrate, suchas a mask (reticle) or a semiconductor wafer. The design layout ismanipulated by mask data preparation 1032 to comply with particularcharacteristics of the mask writer and/or requirements of IC fab 1040.In FIG. 10, mask data preparation 1032 and mask fabrication 1034 areillustrated as separate elements. In some embodiments, mask datapreparation 1032 and mask fabrication 1034 can be collectively referredto as mask data preparation.

In some embodiments, mask data preparation 1032 includes opticalproximity correction (OPC) which uses lithography enhancement techniquesto compensate for image errors, such as those that can arise fromdiffraction, interference, other process effects and the like. OPCadjusts IC design layout 1022. In some embodiments, mask datapreparation 1032 includes further resolution enhancement techniques(RET), such as off-axis illumination, sub-resolution assist features,phase-shifting masks, other suitable techniques, and the like orcombinations thereof. In some embodiments, inverse lithographytechnology (ILT) is also used, which treats OPC as an inverse imagingproblem.

In some embodiments, mask data preparation 1032 includes a mask rulechecker (MRC) that checks the IC design layout that has undergoneprocesses in OPC with a set of mask creation rules which contain certaingeometric and/or connectivity restrictions to ensure sufficient margins,to account for variability in semiconductor manufacturing processes, andthe like. In some embodiments, the MRC modifies the IC design layout tocompensate for limitations during mask fabrication 1034, which may undopart of the modifications performed by OPC in order to meet maskcreation rules.

In some embodiments, mask data preparation 1032 includes lithographyprocess checking (LPC) that simulates processing that will beimplemented by IC fab 1040 to fabricate IC device 1060. LPC simulatesthis processing based on IC design layout 1022 to create a simulatedmanufactured device, such as IC device 1060. The processing parametersin LPC simulation can include parameters associated with variousprocesses of the IC manufacturing cycle, parameters associated withtools used for manufacturing the IC, and/or other aspects of themanufacturing process. LPC takes into account various factors, such asaerial image contrast, depth of focus (“DOF”), mask error enhancementfactor (“MEEF”), other suitable factors, and the like or combinationsthereof. In some embodiments, after a simulated manufactured device hasbeen created by LPC, if the simulated device is not close enough inshape to satisfy design rules, OPC and/or MRC can be repeated to furtherrefine IC design layout 1022.

It should be understood that the above description of mask datapreparation 1032 has been simplified for the purposes of clarity. Insome embodiments, mask data preparation 1032 includes additionalfeatures such as a logic operation (LOP) to modify the IC design layoutaccording to manufacturing rules. Additionally, the processes applied toIC design layout 1022 during mask data preparation 1032 may be executedin a variety of different orders.

After mask data preparation 1032 and during mask fabrication 1034, amask or a group of masks are fabricated based on the modified IC designlayout. In some embodiments, an electron-beam (e-beam) or a mechanism ofmultiple e-beams is used to form a pattern on a mask (photomask orreticle) based on the modified IC design layout. The mask can be formedin various technologies. In some embodiments, the mask is formed usingbinary technology. In some embodiments, a mask pattern includes opaqueregions and transparent regions. A radiation beam, such as anultraviolet (UV) beam, used to expose the image sensitive material layer(e.g., photoresist) which has been coated on a wafer, is blocked by theopaque region and transmits through the transparent regions. In oneexample, a binary mask includes a transparent substrate (e.g., fusedquartz) and an opaque material (e.g., chromium) coated in the opaqueregions of the mask. In another example, the mask is formed using aphase shift technology. In the phase shift mask (PSM), various featuresin the pattern formed on the mask are configured to have proper phasedifference to enhance the resolution and imaging quality. In variousexamples, the phase shift mask can be attenuated PSM or alternating PSM.The mask(s) generated by mask fabrication 1034 is used in a variety ofprocesses. For example, such a mask(s) is used in an ion implantationprocess to form various doped regions in the semiconductor wafer, in anetching process to form various etching regions in the semiconductorwafer, and/or in other suitable processes.

IC fab 1040 is an IC fabrication entity that includes one or moremanufacturing facilities for the fabrication of a variety of differentIC products. In some embodiments, IC fab 1040 is a semiconductorfoundry. For example, there may be a manufacturing facility for thefront end fabrication of a plurality of IC products (front-end-of-line(FEOL) fabrication), while a second manufacturing facility may providethe back end fabrication for the interconnection and packaging of the ICproducts (back-end-of-line (BEOL) fabrication), and a thirdmanufacturing facility may provide other services for the foundryentity.

IC fab 1040 uses the mask (or masks) fabricated by mask house 1030 tofabricate IC device 1060. Thus, IC fab 1040 at least indirectly uses ICdesign layout 1022 to fabricate IC device 1060. In some embodiments, asemiconductor wafer 1042 is fabricated by IC fab 1040 using the mask (ormasks) to form IC device 1060. Semiconductor wafer 1042 includes asilicon substrate or other proper substrate having material layersformed thereon. Semiconductor wafer further includes one or more ofvarious doped regions, dielectric features, multilevel interconnects,and the like (formed at subsequent manufacturing steps).

System 1000 is shown as having design house 1020, mask house 1030 or ICfab 1040 as separate components or entities. However, it is understoodthat one or more of design house 1020, mask house 1030 or IC fab 1040are part of the same component or entity.

FIG. 11 is a flowchart illustrating a method 1100 for fabricating asemiconductor device 1200, according to various aspects of the presentdisclosure. The method 1100 may be part of the operation 820 of themethod 800 of FIG. 8, as mentioned above. As such, the semiconductordevice 1200 may be made based on at least a portion of the design layoutdisclosed herein. For example, the layout design 400′ of FIG. 4 may beused to make the semiconductor device 1200. Thus, the semiconductordevice 500 of FIG. 5 may share some substantially similarfeatures/structures as the semiconductor device 1200.

FIGS. 12A, 12B, 12C, 12D, 12E, 12F, 12G, 12H, 12I, 12J, 12K, 12L, and12M show schematic cross-sectional views of the semiconductor device1200 at various stages of fabrication according to an embodiment of themethod 1100 of FIG. 11. Thus, each of the operations of the method 1100shall be discussed in conjunction with a corresponding one of thecross-sectional views of the semiconductor device 1200 shown in FIGS.12A-12M.

The semiconductor device 1200 may be included in a microprocessor,memory cell, and/or other integrated circuit (IC). It is noted that themethod of FIG. 11 does not produce a completed semiconductor device1200. A completed semiconductor device 1200 may be fabricated usingcomplementary metal-oxide-semiconductor (CMOS) technology processing.Accordingly, it is understood that additional operations may be providedbefore, during, and after the method 1100 of FIG. 11, and that someother operations may only be briefly described herein. Also, FIGS. 12Athrough 12M are simplified for a better understanding of the presentdisclosure. For example, although the figures illustrate thesemiconductor device 1200, it is understood the semiconductor device1200 may comprise a number of other devices comprising transistors,resistors, capacitors, inductors, fuses, etc.

Referring to FIGS. 11 and 12A, the method 1100 begins at operation 1102in which at least a first transistor 1204-1 and a second transistor1204-2 are formed over a substrate 1202, in accordance with someembodiments. The substrate 1202 can include a crystalline siliconsubstrate (e.g., wafer). In some other embodiments, the substrate 1202may be made of some other suitable elemental semiconductor, such asdiamond or germanium; a suitable compound semiconductor, such as galliumarsenide, silicon carbide, indium arsenide, or indium phosphide; or asuitable alloy semiconductor, such as silicon germanium carbide, galliumarsenic phosphide, or gallium indium phosphide. Further, the substrate1202 may include an epitaxial layer (epi-layer), may be strained forperformance enhancement, and/or may include a silicon-on-insulator (SOI)structure.

The transistors 1204-1 and 1204-2 can each include one or morerespective features/structures formed over and/or in the substrate 1202.For example, the transistor 1204-1 includes a gate structure 1206-1, agate sacrificial layer 1208-1 overlaying the gate structure 1206-1, agate spacer 1210-1 with two portions respectively disposed along thesidewalls of the gate structure 1206-1 and gate sacrificial layer1208-1, a first source/drain structure (or region) 1212-1, and a secondsource/drain structure (or region) 1214-1; and the transistor 1204-2includes a gate structure 1206-2, a gate sacrificial layer 1208-2overlaying the gate structure 1206-2, a gate spacer 1210-2 with twoportions respectively disposed along the sidewalls of the gate structure1206-2 and gate sacrificial layer 1208-2, a first source/drain structure(or region) 1212-2, and a second source/drain structure (or region)1214-2. The source/drain structure 1214-1 of the transistor 1204-1 andthe source/drain structure 1212-2 of the transistor 1204-2 may be formedin the same region (e.g., merged with each other), in some embodiments.The transistors 1204-1 and 1204-2 are each formed as a planar MOSFET inthe illustrated embodiment of FIG. 12A (and the following figures). Thatis, respective active regions (e.g., source/drain structures, conductionchannels) of the transistors 1204-1 and 1204-2 are formed recessed froma top boundary of the substrate 1202. However, it is understood thateach of the transistors 1204-1 and 1204-2 can be formed as any ofvarious other transistor configurations (e.g., a CFET, a FinFET, ananosheet transistor) while remaining within the scope of the presentdisclosure.

The gate sacrificial layers 1208-1 and 1208-2 are each formed of siliconnitride, poly-silicon, silicon oxide, the like, or a combinationthereof, for example, using low-pressure chemical vapor deposition(LPCVD) or plasma enhanced chemical vapor deposition (PECVD). The gatesacrificial layers 1208-1 and 1208-2 are each used as a hard mask(sometimes referred to as a hardmask layer) during subsequentphotolithography processes. The gate sacrificial layers 1208-1 and1208-2 may be later substituted by respective interconnect structures(e.g., a VG, a portion of a VD+VG), which shall be discussed below. Thegate spacers 1210-1 and 1210-2 may include silicon oxide (SiO), siliconnitride (SiN), silicon oxynitride (SiON), or other suitable material.The gate spacers 1210-1 and 1210-2 may each include a single layer ormultilayer structure. In some embodiments, the gate spacer 1210-1 may beformed by depositing a blanket layer of the gate spacer 1210-1 by CVD,PVD, ALD, or other suitable technique, and performing an anisotropicetching process on the blanket layer to form a pair of the gate spacer1210-1 respectively along the sidewalls of the gate structure 1206-1(and the gate sacrificial layer 1208-1), as shown in the illustratedembodiment of FIG. 12A. The gate spacer 1210-2 may be formed by thesimilar process, as discussed above.

In some embodiments, subsequently to forming the transistors 1204-1 and1204-2, at least some of the structures of the transistors 1204-1 and1204-2 are overlaid (or embedded) by respective isolation structures(e.g., shallow trench isolation (STI) structures). For example, thesource/drain structures 1212-1, 1214-1/1212-2, and 1214-2 can overlaidby isolation structures 1213-1, 1213-2, and 1213-3, respectively. Suchan isolation structure may include a dielectirc material that isselected from at least one of: silicon oxide, a low dielectric constant(low-k) material, or a combination thereof. The low-k material mayinclude fluorinated silica glass (FSG), phosphosilicate glass (PSG),borophosphosilicate glass (BPSG), carbon doped silicon oxide(SiO_(x)C_(y)), Black Diamond® (Applied Materials of Santa Clara,Calif.), Xerogel, Aerogel, amorphous fluorinated carbon, Parylene, BCB(bis-benzocyclobutenes), SiLK (Dow Chemical, Midland, Mich.), polyimide,and/or other future developed low-k dielectric materials.

Referring to FIGS. 11 and 12B, the method 1100 proceed to operation 1104in which MDs 1216-1 and 1216-2 are formed, in accordance with someembodiments. The MD, in contact with a formed source/drain structure, isgenerally configured to electrically couple the source/drain structureto an interconnect structure (e.g., an M0 track, or an M0 trackportion). For example, the MD 1216-1 is in contact with the source/drainstructure 1212-1 to electrically couple the source/drain structure1212-1 to a corresponding M0 track portion, which shall be shown below.Similarly, the MD 1216-2 is in contact with the source/drain structure1212-2/1214-1 to electrically couple the source/drain structure1212-2/1214-1 to a corresponding M0 track portion, which shall also beshown below.

In some embodiments, the MDs 1216-1 and 1216-2 may be formed byreplacing the isolation structures that overlays the correspondingsource/drain structure with a conductive material. Further, the MDs1216-1 and 1216-2 may be formed at the location where the recessedinterconnect structure, as disclosed herein, is not to be formed. At thelocation where the recessed interconnect structure is to be formed, theisolation structure overlaying the corresponding source/drain featuremay be kept at the current stage. For example, the MDs 1216-1 and 1216-2can be formed by performing at least some of the following processes:forming a mask layer 1215 covering at least the isolation structure1213-3 (where a recessed interconnect structure is to be formed);removing (e.g., etching), with the mask layer 1215 functioning as amask, the isolation structures 1212-1 and 1212-2 to form holes; fillingthe holes with one or more conductive materials; and performing apolishing process (e.g., a chemical-mechanical polishing (CMP) process)to remove excessive conductive material and the mask layer 1215. Theconductive material can include at least one material selected from thegroup consisting of: cobalt (Co), ruthenium (Ru), tantalum (Ta),titanium (Ti), tungsten (W), molybdenum (Mo), zinc (Zn), aluminum (Al),and manganese (Mn). Filling the holes can include one or more depositiontechniques such as, for example, physical vapor deposition (PVD),chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), lowpressure CVD (LPCVD), atomic layer deposition (ALD), and otherwell-known deposition techniques.

Referring to FIGS. 11 and 12C, the method 1100 proceed to operation 1106in which an upper portion of the kept isolation structure 1213-3 isrecessed, in accordance with some embodiments. In some embodiments, anupper portion of the isolation structure 1213-3 may be partially removedto have a height about the same as a height of the gate structure1206-2. In some other embodiments, upon removing the upper portion ofthe isolation structure 1213-3, the height of the isolation structure1213-3 can be lower than or higher than the height of the gate structure1206-2. For example, the upper portion of the isolation structure 1213-3may be removed by performing at least some of the following processes:forming a mask layer 1217 covering at least the MDs 1216-1 and 1216-2,and the gate structures 1206-1 and 1206-2; and partially removing (e.g.,etching), with the mask layer 1217 functioning as a mask, the isolationstructure 1213-3.

Referring to FIGS. 11 and 12D, the method 1100 proceed to operation 1108in which the MDs 1216-1 and 1216-2 are recessed, in accordance with someembodiments. In some embodiments, respective upper portions of the MDs1216-1 and 1216-2 may be concurrently removed. For example, the upperportions of the MDs 1216-1 and 1216-2 may be removed by performing atleast some of the following processes: forming a mask layer 1219covering at least the recessed isolation structure 1213-3, and the gatestructure 1206-2; and partially removing (e.g., etching), with the masklayer 1219 functioning as a mask, the MDs 1216-1 and 1216-2.

Referring to FIGS. 11 and 12E, the method 1100 proceed to operation 1110in which source/drain sacrificial layers 1220-1, 1220-2, and 1220-3 areformed, in accordance with some embodiments. Each of the source/drainsacrificial layers 1220-1, 1220-2, and 1220-3 is formed to overlay acorresponding MD or isolation structure. For example, the source/drainsacrificial layer 1220-1 is formed to overlay the 1216-1; thesource/drain sacrificial layer 1220-2 is formed to overlay the MD1216-2; and the source/drain sacrificial layer 1220-3 is formed tooverlay the isolation structure 1213-3. The source/drain sacrificiallayers 1220-1, 1220-2, and 1220-3 are each formed of silicon nitride,poly-silicon, silicon oxide, the like, or a combination thereof, forexample, using low-pressure chemical vapor deposition (LPCVD) or plasmaenhanced chemical vapor deposition (PECVD). The source/drain sacrificiallayers 1220-1, 1220-2, and 1220-3 are each used as a hard mask(sometimes referred to as a hardmask layer) during subsequentphotolithography processes. The source/drain sacrificial layers 1220-1,1220-2, and 1220-3 may be later substituted by respective interconnectstructures (e.g., a VD, a portion of a VD+VG), which shall be discussedbelow. In some embodiments, the source/drain sacrificial layers 1220-1,1220-2, and 1220-3 may have an etching rate different from an etchingrate of the gate sacrificial layers 1208-1 and 1208-2.

Referring to FIGS. 11 and 12F, the method 1100 proceed to operation 1112in which one of the source/drain sacrificial layers (the source/drainsacrificial layer 1220-3), in accordance with some embodiments. In someembodiments, the method 1100 included removing a source/drainsacrificial layer formed in the location where the recessed interconnectstructure is to be formed. For example, the location of the source/drainsacrificial layer 1220-3 (FIG. 12E) occupies a portion of area where therecessed interconnect structure is to be formed, and thus, thesource/drain sacrificial layer 1220-3 is removed. In some embodiments,the source/drain sacrificial layer 1220-3 is removed by performing atleast some of the following processes: forming a mask layer 1221covering at least the source/drain sacrificial layer 1220-1 and 1220-2and the gate sacrificial layer 1208-1; and removing (e.g., etching),with the mask layer 1221 functioning as a mask, the source/drainsacrificial layer 1220-3. As mentioned above, the etching rates of thegate sacrificial layer 1208-2 and the source/drain sacrificial layer1220-3 with respect to a certain etchant are different. In anembodiment, the source/drain sacrificial layer 1220-3 may becharacterized with a higher etching rate than the gate sacrificial layer1208-2. As such, while etching the source/drain sacrificial layer 1220-3using the mask layer 1221 that does not substantially cover the gatesacrificial layer 1208-2, the gate sacrificial layer 1208-2 may remainsubstantially intact.

Referring to FIGS. 11 and 12G, the method 1100 proceed to operation 1114in which the gate sacrificial layer 1208-2 for the transistor 1204-2 isremoved to form a trench 1224, in accordance with some embodiments. Insome embodiments, the trench 1224 may be formed by performing at leastsome of the following processes: forming a mask layer 1225 covering atleast the source/drain sacrificial layer 1220-1 and 1220-2 and the gatesacrificial layer 1208-1; and removing (e.g., etching), with the masklayer 1225 functioning as a mask, the gate sacrificial layer 1208-2 andan upper portion of one of the pair of the gate spacer 1210-2. The masklayer 1225 can be the same as the mask layer 1221. In such a case, thegate sacrificial layer 1208-2 (FIG. 12F) and the source/drainsacrificial layer 1220-3 (FIG. 12E) may be concurrently or respectivelyremoved using the same mask layer. In some embodiments, the mask layer1221 (and the mask layer 1225) can include a pattern that covers atleast the source/drain sacrificial layer 1220-1 and 1220-2 and the gatesacrificial layer 1208-1 but exposes the gate sacrificial layer 1208-2and the source/drain sacrificial layer 1220-3 (FIG. 12E). In the examplewhere the semiconductor device 1200 (or the portion of the semiconductordevice 1200 shown in FIGS. 12A-M) is made based on the layout design400′, the mask layer 1221 may correspond to a combination of thepatterns 452 and 460 shown in FIG. 4.

As mentioned above with respect to FIG. 12C, in some embodiments, theremained isolation structure 1213-3 may have the same height as the gatestructure 1206-2. In such a case, upon removing the gate sacrificiallayer 1208-2 that overlays the gate structure 1206-2 (and removing theupper portion of the gate spacer 1210-2), a top boundary of the gatestructure 1206-2 and a top boundary of the remained isolation structure1213-3 can be substantially aligned with respect to each other, whichdefines a substantially flat bottom boundary for the trench 1224.

Referring to FIGS. 11 and 12H, the method 1100 proceed to operation 1116in which the trench 1224 is filled with a conductive material to form aninterconnect structure 1226, in accordance with some embodiments. Assuch, the interconnect structure 1226 may inherit the geometry of thetrench 1224, for example, having a substantially flat bottom boundary.In some embodiments, the interconnect structure 1226 includes a firstportion 1226-1, which can overlap the location of a VG that might havebeen formed to connect the gate structure 1206-2, and a second portion1226-2, which can overlap the location of a VD that might have beenformed to couple the source/drain structure 1214-2. Accordingly, theinterconnect structure 1226 may hereinafter be referred to as “VD+VG1226”. In some embodiments, the VD+VG 1226 can be formed by performingat least some of the following processes: filling the trench 1224 withone or more conductive materials; and performing a polishing process(e.g., a CMP process) to remove excessive conductive material. Theconductive material can include at least one material selected from thegroup consisting of: cobalt (Co), ruthenium (Ru), tantalum (Ta),titanium (Ti), tungsten (W), molybdenum (Mo), zinc (Zn), aluminum (Al),and manganese (Mn). Filling the holes can include one or more depositiontechniques such as, for example, physical vapor deposition (PVD),chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), lowpressure CVD (LPCVD), atomic layer deposition (ALD), and otherwell-known deposition techniques.

Referring to FIGS. 11 and 12I, the method 1100 proceed to operation 1118in which a portion of the VD+VG 1226 is removed to form recess 1228, inaccordance with some embodiments. The recess 1228 may be verticallyaligned with the gate structure 1206-2, or overlay a portion of the gatestructure 1206-2 along a direction perpendicular to the direction alongwhich the gate structure 1206-2 is extended. Specifically, the recess1228 may be vertically aligned with the first portion 1226-1. As such,the first portion 1226-1 can have a top boundary vertically lower than atop boundary of the second portion 1226-2, and a bottom boundarydirectly contacting the gate structure 1206-2. Further, a bottomboundary of the second portion 1226-2 may be extended from the bottomboundary of the first portion 1226-1. In some embodiments, the recess1228 may be formed by performing at least some of the followingprocesses: forming a mask layer 1227 with a pattern exposing where therecess 1228 is to be formed; and removing (e.g., etching), with the masklayer 1227 functioning as a mask, a portion of the VD+VG 1226. In someembodiments, the pattern of the mask layer 1227 can partially overlapthe VD+VG 1226. In the example where the semiconductor device 1200 (orthe portion of the semiconductor device 1200 shown in FIGS. 12A-M) ismade based on the layout design 400′, the mask layer 1227 may correspondto the pattern 461 shown in FIG. 4.

Referring to FIGS. 11 and 12J, the method 1100 proceed to operation 1120in which the recess 1228 is filled with a dielectric material, inaccordance with some embodiments. Upon filling the recess 1228 with adielectric material, a dielectric recess structure 1230 can be formed.In some embodiments, the dielectric recess structure 1230 may be formedby performing at least some of the following processes: depositing adielectric material over the semiconductor device 1200; and performing apolishing process (e.g., a CMP process) to remove excessive dielectricmaterial. The dielectric material may include a material selected fromat least one of: silicon oxide, a low dielectric constant (low-k)material, or a combination thereof. The low-k material may includefluorinated silica glass (FSG), phosphosilicate glass (PSG),borophosphosilicate glass (BPSG), carbon doped silicon oxide(SiO_(x)C_(y)), Black Diamond® (Applied Materials of Santa Clara,Calif.), Xerogel, Aerogel, amorphous fluorinated carbon, Parylene, BCB(bis-benzocyclobutenes), SILK (Dow Chemical, Midland, Mich.), polyimide,and/or other future developed low-k dielectric materials.

Referring to FIGS. 11 and 12K, the method 1100 proceed to operation 1122in which one or more sacrificial layers are removed, in accordance withsome embodiments. In the example where the semiconductor device 1200 (orthe portion of the semiconductor device 1200 shown in FIGS. 12A-M) ismade based on the layout design 400′, the operation 1122 may includeremoving the gate sacrificial layer 1208-1 (FIG. 12J), while keeping thesource/drain sacrificial layers 1220-1 and 1220-2. Upon removing thegate sacrificial layer 1208-1, the gate structure 1206-1 may be exposed.In some embodiments, the gate sacrificial layer 1208-1 may be removed byperforming at least some of the following processes: forming a masklayer 1231 covering at least the recessed VD+VG 1226 and the dielectricrecess structure 1230; and performing an etching process to remove thegate sacrificial layer 1208-1. In some embodiments, the etching processmay selectively etch the gate sacrificial layer 1208-1, but keep thesource/drain sacrificial layers 1220-1 and 1220-2 intact.

Referring to FIGS. 11 and 12L, the method 1100 proceed to operation 1124in which one or more interconnect structures VD(s) and/or VG(s) areformed, in accordance with some embodiments. Following the above examplewhere the semiconductor device 1200 (or the portion of the semiconductordevice 1200 shown in FIGS. 12A-M) is made based on the layout design400′, the operation 1124 may include forming a VG 1232 that electricallyconnects the gate structure 1206-1. In some embodiments, the VG 1232 maybe formed by performing at least some of the following processes:filling the hole where the gate sacrificial layer 1208-1 was formed withone or more conductive materials; and performing a polishing process(e.g., a chemical-mechanical polishing (CMP) process) to removeexcessive conductive material. The conductive material can include atleast one material selected from the group consisting of: cobalt (Co),ruthenium (Ru), tantalum (Ta), titanium (Ti), tungsten (W), molybdenum(Mo), zinc (Zn), aluminum (Al), and manganese (Mn). Filling the hole caninclude one or more deposition techniques such as, for example, physicalvapor deposition (PVD), chemical vapor deposition (CVD), plasma enhancedCVD (PECVD), low pressure CVD (LPCVD), atomic layer deposition (ALD),and other well-known deposition techniques.

Referring to FIGS. 11 and 12M, the method 1100 proceed to operation 1126in which respective M0 track portions 1240-1 and 1240-2 are formed, inaccordance with some embodiments. The M0 track portions 1240-1 and1240-2 may be segments of an M0 interconnect structure 1240 divided (orcut) by a cut pattern 1241. Such a cut pattern 1241 may be verticallyaligned with the dielectric recess structure 1230. Following the aboveexample where the semiconductor device 1200 (or the portion of thesemiconductor device 1200 shown in FIGS. 12A-M) is made based on thelayout design 400′, the cut pattern 1241 may correspond to the pattern463 shown in FIG. 4. As such, the gate structure 1206-2 can beelectrically coupled to the M0 track portion 1240-2 through the recessedVD+VG 1226, while being electrically isolated from the M0 track portion1240-1. Specifically, the recessed VD+VG 1226 can electrically connectthe gate structure 1206-2 via the bottom boundary of the first portion1226-1 and the M0 track portion 1240-2 via the top boundary of thesecond portion 1226-2.

In one aspect of the present disclosure, a semiconductor device isdisclosed. The semiconductor device includes a first gate structure. Thesemiconductor device includes a first interconnect structure disposed inan interconnect layer. The interconnect layer is disposed above thefirst gate structure, wherein the first interconnect structure islaterally displaced from the first gate structure. The semiconductordevice includes a second interconnect structure disposed between thefirst gate structure and the interconnect layer. The second interconnectstructure includes a first portion and a second portion. The firstportion and the second portion of the second interconnect structure arelaterally adjacent to each other, and the first portion is verticallyshorter than the second portion by a recess. The first gate structure iselectrically coupled to the first interconnect structure by contactingonly the first portion of the second interconnect structure to the firstgate structure and contacting only the second portion of the secondinterconnect structure to the first interconnect structure.

In another aspect of the present disclosure, a semiconductor device isdisclosed. The semiconductor device includes a first gate structureextending along a first lateral direction. The semiconductor deviceincludes a first interconnect structure, disposed above the first gatestructure, that extends along a second lateral direction perpendicularto the first lateral direction. The first interconnect structureincludes a first portion and a second portion electrically isolated fromeach other by a first dielectric structure. The semiconductor deviceincludes a second interconnect structure, disposed between the firstgate structure and the first interconnect structure, that electricallycouples the first gate structure to the first portion of the firstinterconnect structure. The second interconnect structure includes arecessed portion that is substantially aligned with the first gatestructure and the first dielectric structure along a vertical direction.

In yet another aspect of the present disclosure, a method formanufacturing a semiconductor device is disclosed. The method includesforming a gate structure overlaid by a first sacrificial layer and asource/drain structure overlaid by a second sacrificial layer. Themethod includes replacing the first sacrificial layer and an upperportion of the second sacrificial layer with a first interconnectstructure. The method includes recessing a portion of the firstinterconnect structure, wherein the recessed portion is verticallyaligned with the gate structure. The method includes filling therecessed portion with a dielectric material to form a recesseddielectric structure. The method includes forming a second interconnectstructure over the first interconnect structure, wherein the secondinterconnect structure is cut into a plurality of portions by adielectric structure that is vertically aligned with the recesseddielectric structure.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device, comprising: a first gatestructure; a first interconnect structure disposed in an interconnectlayer, the interconnect layer disposed above the first gate structure,wherein the first interconnect structure is laterally displaced from thefirst gate structure; and a second interconnect structure disposedbetween the first gate structure and the interconnect layer, the secondinterconnect structure including a first portion and a second portion,wherein the first portion and the second portion of the secondinterconnect structure are laterally adjacent to each other, and thefirst portion is vertically shorter than the second portion by a recess,and wherein the first gate structure is electrically coupled to thefirst interconnect structure by physically contacting only the firstportion of the second interconnect structure to the first gate structureand physically contacting only the second portion of the secondinterconnect structure to the first interconnect structure.
 2. Thesemiconductor device of claim 1, wherein the first portion of the secondinterconnect structure is electrically isolated from the firstinterconnect structure and any of other interconnect structures disposedin the interconnect layer by at least a dielectric structure filling therecess.
 3. The semiconductor device of claim 1, wherein the firstportion of the second interconnect structure has a first top boundaryand a first bottom boundary, the first top boundary is vertically andlaterally spaced apart from the first interconnect structure, and thefirst bottom boundary directly contacts a top boundary of the first gatestructure.
 4. The semiconductor device of claim 3, wherein the secondportion of the second interconnect structure has a second top boundaryand a second bottom boundary, the second top boundary directly contactsthe first interconnect structure, and the second bottom boundary islaterally displaced from the top boundary of the first gate structure.5. The semiconductor device of claim 1, wherein the first portion of thesecond interconnect structure is vertically aligned with the recess andthe first gate structure, and the second portion of the secondinterconnect structure is vertically aligned with an end portion of thefirst interconnect structure.
 6. The semiconductor device of claim 1,further comprising: a second gate structure laterally spaced apart fromthe first gate structure; a third interconnect structure disposed in theinterconnect layer, wherein the third interconnect structure islaterally spaced apart from the first interconnect structure; and afourth interconnect structure, disposed between the second gatestructure and the interconnect layer, that connects the second gatestructure to the third interconnect structure.
 7. The semiconductordevice of claim 6, wherein the first gate structure and the second gatestructure are laterally spaced apart from each other by a distance, andwherein a width by which at least one of the first interconnectstructure or the third interconnect structure is laterally extended isequal to or greater than 1.5 times the distance.
 8. The semiconductordevice of claim 6, wherein the first gate structure and the second gatestructure are adjacent two of a number of gate structures thatconstitute a standard cell, the number being equal to or less than
 5. 9.The semiconductor device of claim 1, wherein the first interconnectstructure is included in one of a number of signal tracks disposed inthe interconnect layer, the number being equal to or less than
 3. 10.The semiconductor device of claim 1, wherein the second portion of thesecond interconnect structure is vertically spaced apart from asource/drain structure by an isolation structure, the source/drainstructure being laterally spaced apart from the first gate structure.11. A semiconductor device, comprising: a first gate structure; a firstinterconnect structure disposed in an interconnect layer above the firstgate structure; a second interconnect structure also disposed in thesame interconnect layer, wherein the second interconnect structure islaterally spaced apart from the first interconnect structure; and athird interconnect structure electrically connecting the first gatestructure to the first interconnect structure; wherein the thirdinterconnect structure comprises a first portion and a second portion;wherein the first portion is in physical contact only with the firstgate structure and the second portion is in physical contact only withthe first interconnect structure.
 12. The semiconductor device of claim11, wherein the first portion is shorter than the second portion, withrespective bottom boundaries of the first and second portionssubstantially aligned with each other.
 13. The semiconductor device ofclaim 11, wherein the first portion has (i) a first bottom boundary indirect contact with the first gate structure; and (ii) a first topboundary in direct contact with a dielectric recess structure.
 14. Thesemiconductor device of claim 11, wherein the second portion has (i) asecond bottom boundary laterally shifted from a top boundary of thefirst gate structure; and (ii) a second top boundary having at least aportion in direct contact with the first interconnect structure.
 15. Thesemiconductor device of claim 11, further comprising: a second gatestructure laterally spaced apart from the first gate structure; and afourth interconnect structure, disposed between the second gatestructure and the interconnect layer, that connects the second gatestructure to the second interconnect structure.
 16. The semiconductordevice of claim 15, wherein the first gate structure and the second gatestructure are adjacent ones of a number of gate structures thatconstitute a standard cell, the number being equal to or less than 5.17. The semiconductor device of claim 11, wherein the first interconnectstructure and the second interconnect structure are both included in oneof a number of signal tracks that constitute a standard cell, the numberbeing equal to or less than
 3. 18. The semiconductor device of claim 11,wherein the second portion is vertically spaced apart from asource/drain structure with an isolation structure, the source/drainstructure being laterally spaced apart from the first gate structure.19. A semiconductor device, comprising: a standard cell corresponding toan integrated circuit and comprising a plurality of gate structuresextending along a first lateral direction, wherein a number of the gatestructures is equal to or less than 5; wherein at least a first one anda second one of the gate structures, disposed next to each other, areelectrically connected to a first interconnect structure and a secondinterconnect structure, respectively; wherein the first gate structureis electrically connected to the first interconnect structure through afirst via structure; and wherein the second gate structure iselectrically connected to the second interconnect structure through acombination of a second via structure and a source/drain interconnectstructure, thereby allowing the second interconnect structure tolaterally shift away from the second gate structure.
 20. Thesemiconductor device of claim 19, wherein the second via structure isshorter than the source/drain interconnect structure and shorter thanthe first via structure, and wherein respective bottom boundaries of thesecond via structure and the source/drain interconnect structure aresubstantially aligned with each other.